Fig. 3

Principal coordinate analysis (PCoA) of bacteria in the 16 “sink” studies in this meta-analysis. Communities are compared using the unweighted UniFrac distance metric. a Studies cluster generally by study identity, and the top ten indicator taxa (triangles) are indicative of human-associated bacteria as well as outdoor-derived taxa. b Bacterial community composition also tend to group by the matrix type (the physical sample type) as well as the way the building is used (c)